Impact of Ponderomotive Forces on the Earth’s Magnetosphere

The theory of plasma density redistribution and polar wind acceleration acceleration under the affect on the magnetosphere of the ponderomotive forces induced by the ultra-low frequency electromagnetic waves is presented. Our attention is focused mainly on the important question about the necessity of experimental verification of fairly certain theoretical predictions. It is pointed out that experimental validation is not only necessary for the development of the theory but also for replenishing the knowledge about the structure and dynamics of the near-Earth space. An original method for indirect verification is presented. The idea of this method is based on the dependence of the foreshock locations on the orientation of the field lines of the interplanetary magnetic field (IMF) in front of the magnetosphere relative to the plane of the geomagnetic equator.     

Impact of solar wind tangential discontinuities on the Earth’s magnetosphere

The collision of a solar wind tangential discontinuity with the bow shock and magnetopause is considered in the scope of an MHD approximation. Using MHD methods of trial calculations and generalized shock polars, it has been indicated that a fast shock refracted into the magnetosheath originates when density increases across a tangential discontinuity and a fast rarefaction wave is generated when density decreases at this discontinuity. It has been indicated that a shock front shift under the action of collisions with a tangential discontinuity is experimentally observed and a fast bow shock can be transformed into a slow shock. Using a specific event as an example, it has been demonstrated that solar wind tangential discontinuity affects the geomagnetic field behavior.     

Impact of interplanetary shock on parameters of plasma turbulence in the Earth’s magnetosheath

Data from the BMSW spectrometer, which measures the ion flux value and sometimes plasma parameters with a time resolution of 31 ms, allow the study of the parameters of turbulence of the solar wind and magnetosheath plasma on kinetic scales. In this work, the frequency spectra of the ion flux fluctuations before and after recording the interplanetary shock front in the Earth’s magnetosheath are compared based on these data. It is shown that, in contrast to the solar wind, where the exponential decay of the spectrum often occurs after the shock front on the kinetic scales, no such phenomenon is observed in the magnetosheath: the spectrum on these scales can be approximated by a power function in all the cases considered. In half of these cases, the spectrum slope on the kinetic scales does not change during the interplanetary shock propagation. The results indicate a weak impact of interplanetary shock waves on the parameters of the plasma turbulence. In addition, it is shown that an interplanetary shock does not change the level of intermittency of the ion flux in the magnetosheath at both low and high level before the front.     

Impact of land-use change on hydrological processes in the Maying River basin, China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of China. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest China, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 28.12%, a base flow decline of 35.32%, a drop in the maximum peak discharge of 35.77%, and mean discharge decreases in spring and autumn of 36.05% and 24.87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73%-81%, and that to the influence of base flow reaching 62%-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.     

A Statistical Estimation Model for the Impact Force of Dry Granular Flow Against Rigid Barrier

The impact force on retaining structure, which is caused by granular flow comprised of dry particles originated from shallow landslide failure, still lacks systematic studies. In order to support the potential design requirement of structure used to resist this kind of impact, a series of dry granular impact experiments are conducted on one rigid barrier model. According to parametric analysis results, one nonlinear regression model is proposed to correlate total normal impact force at critical time (F_cr) with its influential parameters. Further, we complete a systematic statistics analysis and obtain a subsequent optimum regression equation based on the proposed model. According to experience and dimension balance, the equation is modified and finally transformed into one non-dimensional equation, which shows good agreement between predicted and observed results.     

Impact of space energetic particles on the Earth’s atmosphere (a review)

The state of the Earth??s upper atmosphere is formed with the participation of impacts by energetic particles, such as galactic cosmic rays, protons of solar proton events, and precipitation of relativistic electrons. Changes in the neutral composition and the thermal and dynamical regime of the upper atmosphere during periods of disturbances caused by the influence of energetic particles are considered.     

Impact of salt stress on the features and activities of root system for three desert halophyte species in their seedling stage

Linkage between belowground and aboveground sections of ecological system is mainly depending on root system. But root system is the parts of plant that people less understand. The absorption function of root system is closely related to their morphology and activity. Moreover root system can interact with the environmental stress under the adverse situation, and adjust its system to take adaptation responses in morphology and physiology to strengthen its survival chance. This research is focused on three desert halophyte species of H. ammodendron (C.A.Mey.) Bge., S. physophora Pall., and S. nitraria Pall. under solution culture, to study the differences of their root system morphology and activity in the seedling stage under varying salt concentration conditions. The study results show that: A certain salt concentration can promote development of these three halophytes; but rather high salt concentration will restrain their growth, in particular inhibit the root system development. Under the same salt concentration condition, S. nitraria Pall. grows fast and accumulates the largest amount of biomass. Under relatively low salt concentration, the length of axial root and the total length of root system of these three halophyte species are all increased; and compared to the checking samples, S. physophora Pall. occupies the top place of root system growth, but the high salt concentration will restrain the increase of total root length; among them, the impact intensity on S. physophora Pall. is lighter than to H. ammodendron (C.A.Mey.) Bge. and S. nitraria Pall. is lighter; the salinity does not bring distinct influence on the average diameter of root system of these three plant species, but trends to reducing the size; under the solution culture conditions, the middle and lower parts of the axial root of H. ammodendron (C.A.Mey.) Bge. and S. physophora Pall. are rather equally distributed, but the central zone of S. nitraria Pall. root system is more significantly increased than the upper and lower zones; salt concentration does not bring significant impact on the root system spatial distribution of each species. The root activity of the three plants is increased along with the increase of the salt concentration. When the salt concentration is low, the root activity is not significantly increased; but when the salt concentration is high, the root activity is increased significantly. The experimental results show that the saline tolerance capacity of H. ammodendron (C.A.Mey.) Bge. is lower than the other two species, and the capacity of S. physophora Pall. ranks the top place.     

Numerical simulation of the influence of lower-crustal flow on the deformation of the Sichuan-Yunnan Region

On the basis of distribution of active fault and regional rheological structure, a three-dimensional finite element model of Sichuan-Yunnan region, China, is constructed to simulate contemporary crustal motion and stress distri- bution and discuss the dynamic mechanism of crustal motion and deformation in the Sichuan-Yunnan region. Lin- ear Maxwell visco-elastic model is applied, which includes the active fault zones, the elastic upper crust and vis- cous lower crust and upper mantle. Four different models with different boundary conditions and deep structure are calculated. Some conclusions are drawn through comparison. Firstly, the crustal rotation about the eastern syntaxis of the Himalaya in the Sicuan-Yunnan region may be controlled by the special dynamic boundary condition. The drag force of the lower-crust on the upper crust is not negligible. At the same time, the main active fault zones play an important role in the contemporary crustal motion and deformation in Sichuan-Yunnan region.     

Impact of ocean–wave coupling on typhoon-induced waves and surge levels around the Korean Peninsula: a case study of Typhoon Bolaven

Typhoon-induced waves and surges are important when predicting potential hazards near coastal regions. In this paper, we applied a coupled modeling system for ocean–wave interaction to examine prediction capabilities for typhoon-induced waves and surges around the Korean Peninsula. To identify how ocean–wave coupling impacts wave and surge simulations during typhoon conditions, a set of comparative experiments was performed during Typhoon Bolaven (2012): (1) a fully coupled ocean–wave model, (2) a one-way coupled ocean–wave model without surface current feedback and ocean-to-wave water levels, and (3) a stand-alone ocean model without considering wave-based sea surface roughness (SSR). When coupled with the ocean model, the surface current reduced significantly the wave height on the right-hand side of the advancing typhoon track and improved prediction accuracy along the southern coast of Korea. Compared with the observed surge levels, the simulated surge height yielded improved results for peak height magnitude and timing compared with the uncoupled model. For wave-to-surge feedback, we found that wave-induced SSR plays an important role by modulating wind stress in the surface layer. The modulated wind stress directly affected the surge height, which improved surge peak prediction during the typhoon.     

Impact of climate and land-use changes on hydrological processes and sediment yield—a case study of the Be River catchment,Vietnam

Abstract

The impact of climate and land-use changes on hydrological processes and sediment yield is investigated in the Be River catchment, Vietnam, using the Soil and Water Assessment Tool (SWAT) hydrological model. The sensitivity analysis, model calibration and validation indicated that the SWAT model could reasonably simulate the hydrology and sediment yield in the catchment. From this, the responses of the hydrology and sediment to climate change and land-use changes were considered. The results indicate that deforestation had increased the annual flow (by 1.2%) and sediment load (by 11.3%), and that climate change had also significantly increased the annual streamflow (by 26.3%) and sediment load (by 31.7%). Under the impact of coupled climate and land-use changes, the annual streamflow and sediment load increased by 28.0% and 46.4%, respectively. In general, during the 1978–2000 period, climate change influenced the hydrological processes in the Be River catchment more strongly than the land-use change.

Editor Z.W. Kundzewicz; Associate editor Q. Zhang

Citation Khoi, D.N. and Suetsugi, T., 2014. Impact of climate and land-use changes on hydrological processes and sediment yield—a case study of the Be River catchment, Vietnam. Hydrological Sciences Journal, 59 (5), 1095–1108.     

Seismotectonic destruction of the Earth’s crust in the zone of interaction of the northeastern side of the Baikal rift and the Aldan-Stanovoy block

The paper presents the modern structural-tectonic pattern and a tectonodynamic model of the zone of interaction of the most seismically active northeastern side of the Baikal rift zone (BRZ) and the conjugate system of seismogenic structures of the Aldan-Stanovoy block, where disastrous events with M ≥ 6.0 have been reported. Regularities in the structural formation of active faults and their kinematics are discussed. The faults form block structures accumulating significant tectonic strain. Motions between large tectonic blocks cause sudden release of the strain, which results in catastrophic events (M ≥ 6.0) with focal mechanisms of definite kinematic type.     

Kinematic features of the seismogenic fault of the Tangshan earthquake and the recurrence period of large earthquakes

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Impact of hillslope vegetation restoration on gully erosion induced sediment yield

As a result of serious soil erosion on the Loess Pla-teau of China, about 1.6 billion tons of silt discharge into the downstream and 0.4 billion tons deposit on the riverbed every year, causing serious threat to the life and property of the local people on both banks of the lower Yellow River[1]. Since the 1950s, the Chinese government has initiated the work on soil and water conservation and environmental management on the Loess Plateau and formulated the guiding principle of hillslope and …     

Manifestation of the Lunar–Solar Tide and Free Oscillations of the Earth in the Variations of the Magnetic Field

The results of processing and analyzing the instrumental observations of the Earth’s magnetic field at the Geophysical Observatory Mikhnevo of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (IGD RAS) for 2010–2015 are presented. Quasi-harmonic components with the periods close to the lunar–solar tidal waves are revealed in the spectra of geomagnetic variations over a period of 0.4 to 30 days. The elliptical S₁ tidal wave which is detected in the geomagnetic variations has modulations with periods of 1/3, 1/2, and 1 year. The spectra of the geomagnetic variations contain peaks corresponding to the free oscillations of the Earth. The analysis of the time series of the magnetic field for the period of the strong earthquakes in the absence of geomagnetic disturbances revealed the fine structure of the Earth’s fundamental spheroidal mode ₀S₂, which splits into five singlets. The established features of the spectrum of geomagnetic variations are helping the development of the new method for studying the deep structure of the Earth and the properties of the inner geospheres for estimating the viscosity of the Earth’s outer core and dynamics of the current systems in the outer (liquid) core, as well as for exploring, with the use of empirical data, the general regularities governing the regimes of energy exchange processes in the geospheres.     

Oil contamination of sedimentary shores of the Galápagos Islands following the wreck of the Jessica

Sediment samples were collected from sandy beaches at a variety of sites in the southern Galápagos Archipelago to assess levels of hydrocarbon contamination following the wreck of the oil tanker Jessica. Hydrocarbon levels in sediments were generally very low by international standards ranging between 0.4 and 48.9 ppm, with contamination attributable to the Jessica only detected at three sites Santa Fe, Playa Estación (Puerto Ayora, Santa Cruz) and Long Beach (Isabela). There was evidence of residual hydrocarbon contamination from sources other than the wreck of the Jessica.     

Dynamical diagnosis of the breakup of the stratospheric polar vortex in the Northern Hemisphere

The research on climate change in polar regions, especially on the role of polar in the global climate system, has gain unprecedented level of interest. It has been the key scientific issue of the International Polar Year program (IPY, 2007―2008). In this paper, we dealt with the debate upon the breakup time of the stratospheric polar vortex in boreal spring. An observational study of the relation between strato- spheric polar vortex breakup and the extra-tropical circulation was performed. The mean breakup date―when the winter westerly at the core of polar jet turns to summer easterly―is about April 10. The breakup time has large interannual variation with a time span of about 2 months. It also has a long-term trend with the 1990s and 2000s witnessing more and more late breakups of polar vortex. Composite of wind speed at the core of polar jet for the extremely early and late breakup years shows that late years have two periods of westerly weakening while early breakup years have only one. The first weakening in the late years happens in middle January with wind speed dropping sharply from more than 40 m s?1 to about 15 m s?1. This is accompanied with anomalous activities of planetary waves in both strato- sphere and troposphere; while the second weakening in the late breaking years is mainly the results of diabatic heating with very weak wave activities. In early breakup years, the transition from westerly to easterly is rapid with wind speed dropping from more than 30 m s?1 to less than ?10 m s?1 within a month. This evolution is associated with a strong bidirectional dynamical coupling of the stratosphere and troposphere. The circulation anomalies at low troposphere are also analyzed in the extremely early and late breakup years. It shows that there are significant differences between the two kinds of extreme years in the geopotential height and temperature composite analysis, indicating the dynamical cou- pling of stratosphere and troposphere with the evolution of stratospheric polar vortex.     

Characteristics of the Activity of the Lintong-Chang＇an Fault in the Late Pleistocene

Analysis of fault outcrops and trench sections indicates fault displacements of 0.2m - 6.0 m on the bottom paleosol layer of the Epipleistocene with the maximum rate of 0.047 mm/a and an average displacement of 1.1 meters. The activity appears as fissures on the fault surface in the late Epipleistocene and there is no obvious displacement. The fault activity is weak and the most active segment is the Bailuyuan segment.